首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   33299篇
  免费   2403篇
  国内免费   55篇
耳鼻咽喉   303篇
儿科学   1187篇
妇产科学   963篇
基础医学   4291篇
口腔科学   434篇
临床医学   4351篇
内科学   5992篇
皮肤病学   473篇
神经病学   3548篇
特种医学   598篇
外国民族医学   4篇
外科学   3003篇
综合类   328篇
一般理论   45篇
预防医学   4632篇
眼科学   512篇
药学   2260篇
中国医学   23篇
肿瘤学   2810篇
  2024年   44篇
  2023年   296篇
  2022年   524篇
  2021年   1128篇
  2020年   685篇
  2019年   1040篇
  2018年   1162篇
  2017年   835篇
  2016年   980篇
  2015年   1010篇
  2014年   1338篇
  2013年   1881篇
  2012年   2747篇
  2011年   2970篇
  2010年   1554篇
  2009年   1301篇
  2008年   2386篇
  2007年   2389篇
  2006年   2186篇
  2005年   2063篇
  2004年   1836篇
  2003年   1589篇
  2002年   1603篇
  2001年   208篇
  2000年   171篇
  1999年   201篇
  1998年   307篇
  1997年   241篇
  1996年   168篇
  1995年   178篇
  1994年   134篇
  1993年   119篇
  1992年   69篇
  1991年   47篇
  1990年   48篇
  1989年   39篇
  1988年   39篇
  1987年   35篇
  1986年   34篇
  1985年   16篇
  1984年   19篇
  1983年   29篇
  1982年   28篇
  1981年   19篇
  1980年   11篇
  1978年   4篇
  1977年   4篇
  1973年   4篇
  1972年   3篇
  1942年   4篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
The National Heart, Lung, and Blood Institute (NHLBI) convened a Working Group (WG) on August 5 to 6, 2010 in Bethesda, Maryland to discuss future directions of research in heart transplantation (HT). The WG was composed of researchers with expertise in the basic science, clinical science, and epidemiological aspects of advanced heart failure and HT. These experts were asked to identify the highest priority research gaps in the field and make recommendations for future research strategies. The WG was also asked to include approaches that capitalize on current scientific opportunities and focus on areas that required unique NHLBI leadership. Finally, the WG was charged with developing recommendations that would have short- and long-term impact on the field of HT. The WG participants reviewed key areas in HT and identified the most urgent knowledge gaps. These gaps were then organized into the following 4 specific research directions: 1) enhanced phenotypic characterization of the pre-transplant population; 2) donor-recipient optimization strategies; 3) individualized immunosuppression therapy; and, 4) investigations of immune and non-immune factors affecting late cardiac allograft outcomes. Finally, because the HT population is relatively small compared with other patient groups, the WG strongly urged concerted efforts to enroll every transplant recipient into a clinical study and to increase collaborative networks to optimize research in this field.  相似文献   
992.
993.
Saccadic eye movements cause large-scale transformations of the image falling on the retina. Rather than starting visual processing anew after each saccade, the visual system combines post-saccadic information with visual input from before the saccade. Crucially, the relative contribution of each source of information is weighted according to its precision, consistent with principles of optimal integration. We reasoned that, if pre-saccadic input is maintained in a resource-limited store, such as visual working memory, its precision will depend on the number of items stored, as well as their attentional priority. Observers estimated the color of stimuli that changed imperceptibly during a saccade, and we examined where reports fell on the continuum between pre- and post-saccadic values. Bias toward the post-saccadic color increased with the set size of the pre-saccadic display, consistent with an increased weighting of the post-saccadic input as precision of the pre-saccadic representation declined. In a second experiment, we investigated if transsaccadic memory resources are preferentially allocated to attentionally prioritized items. An arrow cue indicated one pre-saccadic item as more likely to be chosen for report. As predicted, valid cues increased response precision and biased responses toward the pre-saccadic color. We conclude that transsaccadic integration relies on a limited memory resource that is flexibly distributed between pre-saccadic stimuli.  相似文献   
994.
Patients with end stage liver disease may become critically ill prior to LT requiring admission to the intensive care unit (ICU). The high acuity patients may be thought too ill to transplant; however, often LT is the only therapeutic option. Choosing the correct liver allograft for these patients is often difficult and it is imperative that the allograft work immediately. Donation after cardiac death (DCD) donors provide an important source of livers, however, DCD graft allocation remains a controversial topic, in critically ill patients. Between January 2003-December 2008, 1215 LTs were performed: 85 patients at the time of LT were in the ICU. Twelve patients received DCD grafts and 73 received donation after brain dead (DBD) grafts. After retransplant cases and multiorgan transplants were excluded, 8 recipients of DCD grafts and 42 recipients of DBD grafts were included in this study. Post-transplant outcomes of DCD and DBD liver grafts were compared. While there were differences in graft and survival between DCD and DBD groups at 4 month and 1 year time points, the differences did not reach statistical significance. The graft and patient survival rates were similar among the groups at 3-year time point. There is need for other large liver transplant programs to report their outcomes using liver grafts from DCD and DBD donors. We believe that the experience of the surgical, medical and critical care team is important for successfully using DCD grafts for critically ill patients.  相似文献   
995.
996.

Purpose

Agents targeting the mammalian target of rapamycin (mTOR) pathway, e. g. everolimus, can provide clinical benefit in pretreated patients with metastatic renal cell carcinoma (mRCC), but data from randomized trials on the sequential use of temsirolimus are lacking. We retrospectively studied the efficacy and safety of temsirolimus therapy following failure of rTKI therapy.

Methods

Twenty-nine patients treated with temsirolimus (25 mg/week) following progression on rTKI therapy were studied at four institutions. All patients had failed at least one prior rTKI therapy (sunitinib, n = 6; sorafenib, n = 1; both, n = 22). Over 80% had two or more prior therapies. Data on efficacy (response assessment, progression-free survival [PFS], overall survival [OS]) and safety (NCI-CTC) were analyzed.

Results

Adverse events occurred in 90% of patients with the majority being grade 1 (n = 4, 14%) or grade 2 (n = 12, 41%). Most grade 3/4 toxicities (n = 10, 34%) were manageable and included anemia (n = 4, 14%), leukopenia/neutropenia (n = 2, 7%), hyperglycemia (n = 1, 3%), acidosis/alkalosis (n = 2, 7%), and infection (n = 1, 3%). One patient discontinued temsirolimus for grade 3 pneumonitis. Median (range) PFS and OS were 5.1 months (1–10.4) and 18.0 months (12.6–23.3), respectively. Best response included partial response (n = 1) and stable disease (n = 15) for a disease control rate of 55%, and disease progression of 45% (n = 13).

Conclusions

Temsirolimus after rTKI failure appears to provide promising safety and efficacy comparable to other treatment options in pretreated patients with mRCC.  相似文献   
997.

Purpose

In 2007, the World Health Organization created a Surgical Safety Checklist (SSC) that encompassed a simple set of surgical safety standards. The threefold purpose of this study was to add ambulatory-specific items to the SSC, to introduce the items into an ambulatory surgical facility, and to determine if patient outcomes regarding postoperative pain and nausea/vomiting improved following implementation. In addition, safety attitudes, antibiotic timing, regional anesthesia/nerve blocks, preemptive pain medications, prophylactic antiemetics, length of stay, and hospital admission were also assessed.

Methods

After Research Ethics Board approval, staff complete a Safety Attitudes Questionnaire. Seven items were added to the SSC. Data were then collected on 180 surgical cases before SSC implementation and 195 cases following implementation. Compliance with each section of the SSC was assessed.

Results

On postoperative day one, the median (97.5% confidence interval [CI]) difference between pre- and post-implementation pain scores was 0.5 (97.5% CI, 0 to 1; P = 0.13), and the median difference in the rate of post-discharge nausea/vomiting was ?8.4% (97.5% CI, ?17.9 to 1.1; P = 0.06). There was no improvement in safety attitudes or any of the secondary outcomes, with the exception of the use of preemptive pain medications. Compliance with the three sections of the checklist, i.e., BRIEFING, TIME OUT, and DEBRIEFING was 99.49%, 97.95%, and 96.92%, respectively. There was low compliance in verbalization of the added “ambulatory-specific items”.

Conclusion

Potential reasons for lack of uptake and integration include poor “user” buy-in, an overly lengthy checklist, and lack of prioritization of ambulatory-specific items. A shortened SSC was developed based on the results of this study. This trial was registered at ClinicalTrials.gov ID: NCT00934310.  相似文献   
998.
It is sometimes assumed that dietary fat is required for vitamin D absorption, although the impact of different amounts of dietary fat on vitamin D absorption is not established. This study was conducted to determine whether the presence of a meal and the fat content of the meal influences vitamin D absorption or the 25‐hydroxyvitamin D [25(OH)D] response to supplemental vitamin D3. Based on earlier studies in rats we postulated that absorption would be greatest in the low‐fat meal group. Sixty‐two healthy older men and women were randomly assigned to one of three meal groups: no meal, high‐fat meal, or low‐fat meal; each was given a monthly 50,000 IU vitamin D3 supplement with the test breakfast meal (or after a fast for the no‐meal group) and followed for 90 days. Plasma vitamin D3 was measured by liquid chromatography–mass spectroscopy (LC/MS) before and 12 hours after the first dose; plasma 25(OH)D was measured by radioimmunoassay at baseline and after 30 and 90 days. The mean 12‐hour increments in vitamin D3, after adjusting for age and sex, were 200.9 nmol/L in the no‐meal group, 207.4 nmol/L in the high‐fat meal group, and 241.1 nmol/L in the low‐fat meal group (p = 0.038), with the increase in the low‐fat group being significantly greater than the increases in the other two groups. However, increments in 25(OH)D levels at 30 and 90 days did not differ significantly in the three groups. We conclude that absorption was increased when a 50,000 IU dose of vitamin D was taken with a low‐fat meal, compared with a high‐fat meal and no meal, but that the greater absorption did not result in higher plasma 25(OH)D levels in the low‐fat meal group.  相似文献   
999.

Background

Reconstruction of the nipple–areola complex is the last procedure in breast reconstruction after mastectomy. Various techniques have been described, but the creation of a long-lasting projection represents a challenge in plastic surgery causing frequent nipple projection loss.

Methods

From December 2008 and September 2010, we performed 43 nipple reconstructions using our new technique named “triple-V flap.” This procedure is similar to C-V flap but uses a further V limb area that is de-epithelialized and provides significant support to the new nipple. Clinical assessment was performed with a caliper measuring nipple projection at 1, 6, and 12 months after the surgical procedure.

Results

We evaluated the triple-V nipple reconstruction technique in 43 patients. Reconstructed nipple projection ranged between 3.3 and 6.4 mm (mean 4.8 mm). Mean decrease in nipple projection was 0.2 mm at 1 month, 1.4 mm at 6 months, and 1.6 mm at 1 year. After 1 year, mean nipple projection decrease was 34 %.

Conclusions

Our triple-V technique allows the maintenance of long-lasting projection of the reconstructed nipple at 12 months after surgery. Ease and speed of execution made our technique usable in all patients who need to complete the breast reconstruction process. Level of Evidence: Level IV, therapeutic study.  相似文献   
1000.

Objective

To examine the effect of a 12-week Wellness and Exercise (W&E) program on the quality of life of pediatric burn survivors with burns of ≥40% total body surface area. We hypothesized this comprehensive regimen would improve physical and psychosocial outcomes.

Methods

Children were recruited for participation upon their discharge from the ICU. They were not taking anabolic/cardiovascular agents. Seventeen children participated in the W&E group and 14 children in the Standard of Care (SOC) group. Quality of life was assessed with the Child Health Questionnaire (CHQ) at discharge and 3 months. Children completed the CHQ-CF 87 and caregivers completed the CHQ-PF 28.

Results

The mean age of children in the W&E group was 14.07 ± 3.5 years and mean TBSA was 58 ± 11.8%. The mean age of children in the SOC group was 13.9 ± 3.1 years and mean TBSA was 49 ± 7.8%. ANOVA did not reveal statistically significant differences between the groups. Matched paired t-tests revealed that parents with children in the W&E group reported significant improvements with their children's physical functioning, role/social physical functioning, mental health, overall physical and psychosocial functioning after exercise.

Conclusions

These results are clinically relevant in that a comprehensive W&E program may be beneficial in promoting physical and psychosocial outcomes.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号